Enzyme-linked immunosorbent assay for the pyrethroid permethrin

Permethrin is a predominant pyrethroid widely used in agriculture and publi c health. A competitive enzyme-linked immunosorbent assay (ELISA) for the d etection of permethrin was developed. Two haptens, the trans- and cis-isome rs of 3-(4-aminophenoxy)benzyl-3-(2,2-dichloroethenyl)-2,2-dimethylcyclopro panecarboxylate, were synthesized and conjugated with thyroglobulin as immu nogens. Four antisera were generated and screened against six different coa ting antigens. The resulting ELISA has an I-50 value of 2.50 mu g/L and rel atively low cross-reactivities with other major pyrethroids, such as esfenv alerate, cypermethrin, deltamethrin, and cyfluthrin. Methanol was found to be the best solvent for this ELISA, with optimal sensitivity observed at a concentration of 40% (v/v). The assay parameters are unchanged at pH values between 5.0 and 8.0, whereas higher ionic strengths (>0.2 M PBS) strongly suppress the absorbances. River water samples fortified with permethrin wer e analyzed according to this method and validated by GC-MS. Good recoveries and correlation with spike levels were observed, suggesting this immunoass ay is valuable for environmental monitoring and toxicological studies at pa rts per trillion levels of permethrin.